A lamp is used to illuminate objects. Color rendering index (CRI) is a measure of the lamp's color in achieving color fidelity of the illuminated object's colors. Objects to be illuminated by a lamp may be coated with brighteners (also known as optical brightening agents and fluorescent brightening agents). Brighteners may be fluorescent chemicals that are applied to items, such as clothing and paper. The brighteners may absorb light in the ultraviolet and violet spectral regions, and emit light in the blue spectral region. The brighteners thereby brighten and color-enhance the items that the brighteners are applied to.